Investigations began in 2013 and detected the existence of four criminal gangs, almost daily, landed and took off their planes of Salto del Guaira, in Paraguay, to clandestine airstrips in the state of São Paulo.

The goods were then removed from the aircraft and taken to storage warehouses, where they were transported by trucks and other vehicles to recipients.

During the calculations, the police found that at least 12 aircraft were used by criminals, making up to two flights per day. Each aircraft carried about 600 kilograms of goods, an estimated value of US $ 500 thousand dollars for shipping.

Criminal groups, responsible for freight, were hired by bookies based in Foz do Iguaçu, Parana, and Paraguay. Besides that, one of these organizations marketed goods in own companies, established in Ribeirão Preto and São Paulo.

Throughout the investigations, They were seized four aircraft, one being a single-engine, targeted by the Brazilian Air Force - FAB, in October 2015, when I tried to return to Paraguay loaded goods.

The operation name refers to Greek mythology. Celeno is a harpy - a mythological monster - and the name has the meaning of obscure or darkness.